NL8203542A - POLYMER COMPOSITION. - Google Patents

Abstract

Polymer composition consisting of: A. 5-90 % (wt) of one or more graft copolymers obtained by polymerizing 10-90 parts by weight of a monomer mixture consisting of 20-40 % (wt) acryl compound, 60-80 % (wt) vinylaromatic compound, and 0-20 % (wt) of one or more other unsaturated compounds, in the presence of 10-90 parts by weight rubber; B. 0-70 % (wt) of one or more copolymers obtained by polymerizing 60-80 parts by weight vinylaromatic compounds, 20-40 parts by weight acryl compounds, 0-20 parts by weight of one or more other unsaturated compounds; C. 5-90 % (wt) of one or more polycarbonates; and D. 0.5-25 % (wt) of one or more polyurethanes. In addition to a good petrol resistance, this composition also has very good processing characteristics.

Description

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Stamicarbon B.V.

Inventors: Eduard J. FRENCKEN, in Bergen op Zoom Nicolaas G.M.HOEN, in STEIN Theodorus B.R. DRUMMEN in Hoensbroek 1 PN 3A05

POLYMER COMPOSITION

The invention relates to a polymer composition based on a polycarbonate, a graft copolymer and an elastomeric polyurethane.

Such a polymer composition is known from Dutch Patent Application 7300479 laid open to public inspection. This application relates to a polymer composition consisting of a predominant amount (more than 90 Z) of polycarbonate, a small amount (less than 2 Z) of graft copolymer and a modifying agent such as polyethylene or a polyurethane elastomer.

It is known from various publications that mixtures of polycarbonate (PC) with a graft copolymer of styrene and acrylonitrile on a rubber (ABS) have favorable properties. Examples of such publications are German Pat. Nos. 1,170,141 and 1,810,993, Netherlands Patent Applications Laid-open 7316731 and 7316733, or European Patent Applications 146, 5,202 and 51,336 laid open to public inspection.

The ABS / PC compositions have favorable properties with regard to processability, heat resistance and impact resistance at room temperature. These properties make these compositions particularly suitable for a variety of automotive applications, such as dashboards, bumpers, grilles, and other automotive parts.

However, it has been found that for applications where high impact resistance at very low temperatures (for example -40 eC) is required, these polymer compositions are less suitable. In addition, in certain cases the resistance to organic solvents, such as gasoline, may be unsatisfactory.

It is one of the objects of the present invention to provide a polymer composition which combines the aforementioned favorable properties of ABS / PC compositions with high impact temperature at low temperature, and good gasoline resistance.

According to the invention, such a polymer composition A. comprises 5-90% by weight of one or more graft copolymers obtained by 10-90% by weight of a monomer mixture consisting of 20-40% by weight acrylic compound, 60-80% by weight vinyl aromatic compound, and 0-20% by weight of one or more other unsaturated compounds, to polymerize in the presence of 10-90 parts by weight of rubber, 10 B. 0-7% by weight of one or more copolymers obtained by 60-80% by weight parts of vinyl aromatics, 20-40 parts by weight of acrylic compounds, 0-20 parts by weight of one or more other unsaturated compounds to polymerize, 15 ° C. 5-90% by weight of one or more polycarbonates, and D. 0.5 -25% by weight of one or more elastomeric polyurethanes.

It has surprisingly been found that when the ABS / PC composition is combined with one or more elastomeric polyurethanes, a product is obtained which has a very good impact resistance at low temperature. However, this does not come at too great a cost at the expense of the processing behavior or the heat resistance. In particular, the processing behavior is still significantly improved.

Moreover, the composition according to the invention has an improved resistance to UV radiation as well as to abrasion.

The gloss of the composition is lower than that of the ABS / PC composition, which is particularly advantageous for applications in the automotive industry.

Suitable acrylic compounds for use in the present invention are acrylonitrile, methacrylonitrile alkyl acrylate, alkyl-30 methacrylate or mixtures thereof. Preference is given to acrylonitrile in the graft copolymer A and / or the copolymer B.

Suitable vinyl aromatic compounds are styrene and substituted styrene compounds such as α-methyl styrene, ρ-vinyl toluene, halogenated styrene or mixtures thereof. Preference is given to the use of styrene or a methylstyrene.

In certain cases, it may be preferable to use both styrene and 8203542 3α-methylstyrene, especially the use of styrene in the graft copolymer and <x methylstyrene in the copolymer, or vice versa.

The rubber content of the graft copolymer is preferably between 15 and 50% by weight, based on the graft copolymer.

In order to achieve an optimal ratio between impact strength and processing behavior (flow), it may be advantageous to use two or more graft copolymers, with different rubber contents. For optimum effect, it is desirable that the rubber contents between the different graft copolymers differ by at least 5% by weight, based on the graft copolymer.

Although in principle all rubbers with a glass transition temperature below -30 ° C can be used, preference is given to rubbers with a glass transition temperature below -55 ° C, since the impact strength of the graft copolymer component tends to decrease in the near the glass transition temperature.

More in particular, a butadiene rubber is used, such as polybutadiene, butadiene-styrene, butadiene-acrylonitrile or butadiene-acrylate rubber.

However, in view of, for example, UV resistance, it may be desirable to deviate from the above considerations and choose another rubber, such as an EPDM rubber, as the graft base. However, this can be at the expense of the impact resistance at a very low temperature.

In principle, all thermoplastic polycarbonates are suitable for the compositions of the invention. Polycarbonates are known per se and can be obtained by reacting dihydroxy or polyhydroxy compounds with phosgene or diesters of carbonic acid.

Particularly suitable dihydroxy compounds are dihydroxy-diarylalkanes, including those compounds, which contain alkyl groups or chlorine or bromine atoms in the o position relative to the hydroxyl group.

The following compounds are preferred dihydroxydiarylalkanes: 4,4'-dihydroxy 2,2 diphenylpropane (bisphenol A), tetramethyl bisphenol A, tetrachlorobisphenol A, tetrabromobisphenol A and bis- (4-hydroxyphenyl) p-diisopropylbenzene. In addition to the polycarbonates 8203542 4 which can be prepared from dihydroxydiarylalkanes alone, it is also possible to use branched polycarbonates. For the preparation of polycarbonates of this type, part of the dihydroxy compound, for example 0.2-2 mol%, is replaced by a polyhydroxy-5 compound.

Polycarbonates of the aforementioned type are described, for example, in U.S. Pat. Nos. 3,028 * 365; 2,999,835; 3,148,172; 3,271,368; 2,970,137; 2,991,273; 3,271,367;

In case the polymer composition is to have flame-extinguishing properties, the polycarbonate component can advantageously consist wholly or partly of halogenated polycarbonate.

Polycarbonate can be prepared in a manner known per se, for example as described in the above patents.

Both the preparation of the graft copolymer and the copolymer are suitable for various polymerization techniques, such as emulsion, suspension, mass and solution polymerization, or mixtures thereof such as mass suspension, emulsion mass and emulsion suspension polymerization.

Emulsion polymerization is preferred for the preparation of the graft copolymers. In this technique, very good high-impact-resistant products are obtained in a simple manner.

The copolymer is preferably prepared in emulsion or suspension. Both for the graft copolymers and for the copolymer, it is possible to use the usual techniques in emulsion polymerization.

In the polymerization in aqueous emulsion, the necessary conventional auxiliaries must be used, such as emulsifiers, lye, salts, soaps, initiators such as peroxides, and chain length regulators.

Suitable chain length regulators are organosulfur compounds such as the commonly used mercaptans as well as the dialkyldixantogens, diarylsulfides, mercaptothiazoles, tetraalkylthiurammono- and disulfides, etc., separately or mixed together, as well as hydroxyl compounds such as terpinolenes. In addition, the dimer of α-methylstyrene or a relatively long chain cc-olefin can also be used.

8203542 5

The commercially most commonly used chain length regulators are mainly the mercapto compounds, of which the hydrocarbyl mercaptans with 8-20 carbon atoms per molecule are currently widely used. More particularly, preference is given to mercaptans having a tertiary alkyl group.

The amount of organosulfur compound can vary widely depending on the mixture selected, the specific compound, polymerization temperature, emulsifier and other recipe related variables *. A good result can be achieved by using 0.01-5 parts by weight (per 100 parts by weight of monomer) of organosulfur compound, with 0.05-2 parts being preferred. Suitable organosulphur compounds comprise n-octyl mercaptan, n-dodecylmercaptan, tertiary dodecylmercaptan, tertiary nonylmercaptan, tertiary hexadecylmercaptan, tertiary octadecylmer 15-mercaptan, tertiary eicosyl, secondary octyl mercaptan, secondary tridecyl mercaptan, cyclododecyl, cyclododecadienyl mercaptan, aryl mercaptan such as 1-naphthalene thiol, etc., bis (tetramethylthiuram disulfide), 2-mercaptobenzathiazole and the like. Mixtures of these compounds can also be used.

As an emulsifier, very different compounds can be used, such as disproportionated resin soap, fatty acid soap, mixtures of these compounds, aryl sulfonates, alkyl aryl sulfonates and other surface active compounds and mixtures thereof. Non ionic emulsifiers can also be used such as polyethers and polyols.

The amounts of the emulsifiers used depend on the type, as well as the reaction parameters and the concentrations of polymerizable monomer in the emulsion polymerization system.

Suitable free radical-providing compounds for the emulsion polymerization process are organic or inorganic peroxides, hydroperoxides, azo compounds, as well as redox initiator systems. These compounds can be added at the beginning of the polymerization. It is also possible to add these compounds partly at the beginning, partly during the course of the polymerization.

Preferably, alkali or ammonium persalts and / or redox systems are chosen as initiators. Particular mention should be made of potassium persulfate, ammonium persulfate and sodium persulfate. Examples 8203542 6 of suitable redox systems are persalts (eg, perchlorates or persulfates), tertiary butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide and methylcyclohexyl hydroperoxide, combined with reducing agents based on acids containing sulfur in a valency, sodium sulfide pyrosulfide, sodium sulfide formaldehyde sulfide, sodium sulfide formaldehyde sulf. organic bases such as triethanolamine, with dextrose, sodium pyrophosphate and mercaptans or combinations thereof, optionally in combination with metal salts such as ferrous sulfate. These initiators or initiator systems can be dosed at once, stepwise or even gradually.

When the preparation of the copolymer is carried out in suspension, the usual auxiliary substances are used, such as suspending agents, chain length regulators and free radical-providing compounds.

Suitable suspending agents are polyvinyl alcohols, partially saponified polyvinyl acetate, sparingly soluble metal phosphate compounds and the like. The chain length regulators and the free radical-providing compounds can in principle be the same as in emulsion polymerization.

In order to obtain a polymer composition with a good impact strength, it is preferred to start from a rubber latex with a weight-average particle size (d 50, determined by electron microscope) between 0.05 and 0.70 µm.

This therefore means that in such a case the preparation of the graft copolymer 25 takes place at least partly in emulsion.

The process according to which this rubber latex is prepared is preferably controlled so that highly cross-linked products are obtained. The gel content should preferably be greater than 70% by weight (determined in methyl ethyl ketone or toluene). At high levels of butadiene in the rubber, this degree of cross-linking can be achieved by polymerizing to high degrees of conversion or by using cross-linking agents, ie, polyfunctional monomers, such as divinylbenzene or ethylene glycol dimethacrylate.

If an emulsion polymerization is not used for the graft copolymerization, rubbers made from organic solvent solutions thereof can also be used. However, it is desirable in that case to conduct the graft polymerization reaction, for example, in the form of a bulk slurry polymerization reaction.

In those cases where the rubbers are prepared by emulsion polymerization, the emulsifiers, activators and polymerization auxiliaries used to prepare the copolymer or graft copolymers can be used. Before the grafting reaction, the rubber latex must be degassed in order to suppress undesired reactions initiated by unreacted monomer.

It is preferred to use polybutadiene homopolymers or butadiene copolymers with a butadiene content of more than 60% by weight. If other dienes, for example, isoprene, or the lower alkyl esters of acrylic acid, are used as comonomers, the butadiene content of the rubber can be reduced to 30% by weight, without any disadvantage regarding the properties of the polymer composition. In principle, it is also possible to prepare the graft copolymers from saturated rubbers, for example from 20 ethylene-vinyl acetate copolymers with a vinyl acetate content of less than 50% or from ethylene-propylene-diene terpolymers (these should not be conjugated; examples are: 1,4 hexadiene, ethylidene norbornene, dicyclopentadiene), as well as acrylic rubber, chlorinated polyethylene or chloroprene rubber. Mixtures of two or more rubbers can also be used.

Known elastomeric polyurethanes can be used as polyurethane. These polyurethanes can be prepared by reacting diisocyanate and one or more dihydroxy compounds.

Suitable dihydroxy compounds are the polyoxyalkylene glycols built up of C2-4 oxyalkylene units, such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol, polylactone diols, derived from a lactone containing 5-12 C atoms, such as, for example, hydroxyl-terminated polycaprolactone, polyolactol, polyvalerol polylactones and hydroxyl-terminated polyesters.

In some embodiments, in addition to the above mentioned diol, a low molecular weight diol which can act as a chain extender is also used. Dihydroxyl compounds with a molecular weight between 60 and 200 can be used. Examples are aliphatic straight chain diols such as ethylene glycol, 1,4-butanediol, and 1,6-hexanediol, branched diols such as 1,2-propylene glycol and 2,2-dimethylbutanediol 1.4, low molecular weight polyalkylene glycols such as diethylene glycol, triethylene glycol, or cycloaliphatic diols such as 1,4- (hydroxymethyl) cyclohexane.

As diisocyanates, the usual aromatic, aliphatic or cycloaliphatic compounds in pure or crude form are used, such as toluene diisocyanates, 4.4 diisocyanate diphenylmethane, polyarylene polyphenylisocyanates, isophorone diisocyanate and hexamethylene diisocyanate. An amount of diisocyanate is used such that the total NCO / OH ratio is about 1: 1, for example 1.00: 1 to 1.05: 1.

In general, one or more catalysts are also used which accelerate the isocyanate reactions. The most common types are the polyamino compounds, for example triethylenediamine, and tin-containing compounds, for example dibutyltin diacetate or 20-dilaurate.

The polyurethane component of the polymer composition is preferably prepared from one or more polyesters with hydroxy end groups. These polyesters, in turn, can be prepared either by condensation of approximately equivalent amounts of a glycol and a dicarboxylic acid (or an anhydride thereof), or by reaction of a lactone with at least 6 carbon atoms in the lactone ring and a small amount of bifunctional initiator such as a glycol and amino alcohol or a diamine. In any case, a polyester with a relatively high molecular weight is preferably used, that is to say with a molecular weight of at least 1000.

In the condensation of a glycol and a dicarboxylic acid, the glycol preferably contains 2-6 carbon atoms. Suitable glycols are ethylene, trimethylene, tetramethylene, hexene and propylene glycols. The dicarboxylic acid is preferably aliphatic and contains from 2 to 8 carbon atoms, preferably cinnamic acid, glutaric acid, adipic acid and the like. This condensation polymerization of these polyesters is carried out in a known manner in 8203542 * 9.

When the polyester is prepared on the basis of a lactone, caprolactone is preferably used. The polymerization can then be carried out in a simple manner by mixing the lactone in the bifunctional initiator at an elevated temperature, for instance between 120-200 ° C. Preferably, a catalyst is used at a concentration of about 1/1000 to 1/2 weight percent. Various known catalysts are useful. More detailed information on the preparation of lactone-based polyesters can be found in U.S. Pat. Nos. 2,933,477 and 2,933,478.

The linear dihydroxypolyesters described above can be reacted later with an excess of a, preferably aromatic, diisosyanate, such as 4,4'-diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI). This reaction, which preferably takes place at a temperature between 80-120 ° C, produces a prepolymer, which consists of a mixture of the excess unreacted diisocyanate and a diisocyanate-terminated polymer diol. This mixture can then be reacted with a chain extender in proportions such that all free isocyanate groups have reacted. The chain extender may be a low molecular weight glycol such as ethylene glycol, 1.4 butane diol, and 1.6 hexamethylene glycol.

A very suitable polyurethane of the present invention can be prepared from 1 molar equivalent of a dihydroxy polyester, 6 molar equivalents of diisocyanate and 5 molar equivalents of chain extender. In general, it is preferred to use 2-6 grams of diisocyanate molecules per gram of dihydroxypolyester molecule.

The polyurethanes used can be cross-linked. This can be easily achieved by using a small excess of diisocyanate or using a 3 or polyvalent compound.

The polymer composition may additionally contain various additives such as pigments, fillers, stabilizers, antioxidants, lubricants, antistatics, flame extinguishers and the like.

The invention is illustrated by the following example.

8203542 i ίο

Example

Starting from 70 wt. parts of graft copolymers obtained by polymerizing a mixture of styrene and acrylonitrile In emulsion In the presence of a rubber latex (rubber content in the graft copolymer 5 20 wt%), and 30 wt. parts of polycarbonate (Lexan 121, RTM from General

Electric Plastics), a mixture was made and pressed into test plates.

A second blend was prepared starting from the same graft copolymer and the same polycarbonate in the same weight-10 ratio, with a thermoplastic polyurethane (Estane 5702 / F1, RTM from Goodrich) added thereto. The thermoplastic polyurethane content in the mixture was 5% by weight. The results of the tests are shown in the table.

Table

15 I II

PUR% 05

Melt index dg / min 6.8 19.0 E-modulus N / mm ^ 2225 2150

Vicat non-tempered 1 kg 109.3 108.6 20 5 kg 100.7 99.2 VEM (J) + 23 ° C 1.8 3.2 - 40 ° C 1.5 2.6

This table clearly shows that the Val-Energy Measurement 25 of the mixture with polyurethane has been greatly improved. The VEM is a direct measure of the impact strength of the product made from the blend.

8203542

Claims (7)

11 PN 3405 Polymer composition based on a polycarbonate, a graft copolymer and a polyurethane elastomer, characterized in that the polymer composition comprises: A. 5-90 wt.% Of one or more graft copolymers obtained by 5 10-90 wt. Parts of a monomer mixture consisting of 20-40 wt% acrylic compound, 60-80 wt% vinyl aromatic compound, and 0-20 wt% of one or more other unsaturated compounds, to be polymerized in the presence of 10-90 parts by weight of rubber, 10 B. 0-70 wt% of one or more copolymers obtained by polymerizing 60-80 parts by weight of vinyl aromatic compounds, 20-40 parts by weight of acrylic compounds, 0-20 parts by weight of one or more other unsaturated compounds, C. 5-90% by weight of one or more polycarbonates, and D. 0.5-25% by weight of one or more elastomeric polyurethanes. Polymer composition according to claim 1, characterized in that acrylonitrile is used as the acrylic compound in A and / or B. Polymer composition according to claim 1 or 2, characterized in that the vinyl aromatic compound in A and / or B is styrene and / or CMethylstyrene. Polymer composition according to any one of claims 1-3, characterized in that the rubber content in A is between 15 and 40% by weight. Polymer composition according to any one of claims 1-4, characterized in that 25-75 wt% A, 0-45 wt% B, 25-75 wt% C, and 5-25 wt% D is present. 30 6 * Polymer composition substantially as described and illustrated by the example. 7. Object wholly or partly consisting of a polymer composition according to claims 1-6. 8203542